Method of making molded rubber articles, mold, and lubricant therefor



Patented Apr. 13, 1926.

UNITED STATES PATENT OFFICE.-

IBENTON DALES WILLIAM S. CABLE, OF AKRON, OHIO, ASSIGNORS TO THE F.

GOODRICH ('JOMPANY, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

METHOD MAKING- MOLDED RUBBER ARTICLES, MOLD, AND LUBRICANT THEREFOR- NoDrawing.

To all whom it may concern: 1

Be it known that We, BENg'oN DALES and WILLIAM S. CABLE, citizens of theUnited States, residin at Akron, in the county of 5 Summit and tate of.Ohio, have invented certain new and useful Methods of Making MoldedRubber Articles, Molds, and Lubricants Therefor, of which the followingis a specification. a

This invention relates to hollow rubber articles formed and vulcanizedupon mandrels or cores, such as battery jars, and similar one-piececontainers, and has for an object to provide an improved method ofmaking rubber articles of this character which shall roduce upon. the.vulcanized articles man rel-formed surfaces to which sealing compoundsnormally employed in securing covers to containers will tightly and 0permanently adhere. .A further object is to provide an improvedmandrel-lubricant.

It has heretofore been the usual practice in the manufacture of batteryjars and other one-piece containers to coat the mandrel with soap orwater-glass prior to placing the rubber stock about the mandrel. Thesemandrel lubricants, so-called, prevent effectively the adhesion of therubber to the mandrel during vulcanization but are ob- 80 jectionable inthe manufacture of battery jars in that they leave on the-vulcanizedcontainer a water-soluble film. This is objfctionable for the reasonthat, after the attery has been charged and the cover 3 sealed in placeby means of a suitable sealing compound, the battery liquid seepsupwardly along and thru the water soluble film and loosens the sealingcompound from the jar with the result that the ar leaks and slowlydissipates the liquid content of the battery.

This objectionable loosening of the cover sealin compound is overcomein'accordance'" with t e present invention by the employment of mandrellubricants which are nonsoluble in water and contain no water solublematerials. Not all substances which meet this condition, however, aresatisfactory for this purpose. Oils, fats, fatty-acids, animal waxes,solid hydrocarbons like the parafiins, shellac and resins, whilenon-soluble in water, are of no value as mandrel? lubricants, becausethe are absorbed by the hot rubber during vu canization, and as aApplication filed Noveprber 17, 1924; Serial No. 750,478.

consequence the jar sticks to a greater or a lesser extent to themandreli We have discovered as a result of extended investigations thatwaxes of vegetable origin enerally possess the essential properties 0nonsolubility in water and resistance to absorption in rubber atvulcanization temperatures. Montan wax, carnauba wax, candelilla wax andsugar cane wax are particularly satisfactory as mandrel lubricants, andmay be employed with excellent results in the manufacture of batteryjars.

In carrying out the present invention, about 5 parts by weight of Montanwax, for example, are dissolved in 100 parts by weight of benzol orgasoline, or other organic solvents or mixtures thereof. Both the waxand the solvent should be substantially free of water soluble materials.This solution is then spread on a clean mandrel and allowed to dry. Theresulting surface may then bev covered with rubber cement in the usualway, the rubber built up on the mandrel and the regular curing processcarried through. In the particular case of battery jars, the vulcanizedarticle is found to strip readily from the mandrel, and the film oflubricant left on the vulcanized jar to adhere tightly to the sealingcompounds employed in securing the covers in place, since the liquidcontent of the jar is unable to penetrate the film of the man drellubricant and hence to loosen the bond between jar andsealing compound.

Certain water insoluble materials may be mixed with an of the waxesherein-above mentioned to orm a less expensive lubricant, which willnevertheless be satisfactory. We have found that 2 parts of pitch, 1part of wax, and 60 parts of organic solvent, or substantially a 5%solution, may be employed in place of the solution of Montan wax withgood results. Various pitches may be used in this admixture. Softpitches of an asphaltic or bitumen type, however, are best adapted forthese mandrel lubricants. With hard rubber containers, we find thatMontanwax alone as a lubricant gives a tainers but that with the,pitch-wax mixture, the vulcanized articles slip fromthe mandrels atrifle easier.

' In practice, it is necessary to coat with the wax or the wax-pitchsolution only that .better, smoother surface to vulcanized conpart-ofthe mandrel u on which the upper more easily from the mandrel. if theselug cavities and contiguous portions of the mandrel are first coatedwith asoap solution,

.and then the "remainder of the mandrel covered with a waxsolution ofthe character above described.

\Vhereelec'tric leakage tests are made on the jars b'efore'.vulcanization, a solvent for the wax consistin in "whole or in part of carbontetrachlori e should be-used in order to prevent fires and explosionsduring test.

Modifications may be resorted to within the scope of our invention andwe do not wholly limit our claims to the exact procedure or ingredientsherein described.

We claim:

1. The method of preparing surfaces of members contacting with rubberduring vulcanization which consists in coating the surfaces" at least-inpart with a substantially water-insoluble composition comprising a waxresistant'to absorption in rubber at temperatures of vulcanization.

2:" The method of preparin surfaces of members contacting with ru berduring vulcanization which consists in cost the surfaces at least inpart with a substantially water-insoluble composition comprising a waxof vegetable origin resistant to absorp tion in rubber tion.

3. The method j of members contacting with rubber during vulattemperatures of vulcanizacanization which consists in coating thesurfacesat least in part with a substantially water insolublecomposition comprising Montan wax. p

4... The method of preparing surfaces of members contacting with rubberduring vulcanizatiou which consists in coating the surfaces .at leastin. part with a substantially water-insoluble composition comprising awax of vegetable origin. and a soft pitch of the s halt type.

e method 5. of preparing; surfaces of members contacting withrubberduring 7 vulcanization which consists in coating the reparing surfacesof surfaces at least in part with a substantially water-insolublecomposition comprismg Montan wax and asphaltum pitch.

6. A mold element coated at least in, part with a substantiallywater-insoluble composition'v comprising a wax resistant to absorptionin rubber at temperatures of vulcanizanon.

7 A mold element coated at least in part with a substantiallywater-insolublecomposition comprising a wax of vegetable originresistant to absorption in rubber at temperatures of vulcanization.

8. A mold element coated at least in part with a substantiallywater-insoluble composition comprising Montan wax;

9. A mold elementcoated at least in part with a substantiallywater-insoluble composition com rising a wax of ve etable origin and aso fiitch of the aspha t. type.

10. A-mold. ement coated'at least in part with a substantiallywater-insoluble com position comprising Montan wax and asphaltum pitch.

11. non-adherent coating for surfaces contacting with .rubberduringvulcanization consisting of a substantially water insoluble compositioncomprising a 'wax' resistant to absorption in rubber' at temperatures ofconsisting of'a substantially water-insoluble com osition comprisingawaxfof.

ble

origin resistant to absorption' in i'u rat temperatures ofvulcanization! 13. A non-adherent coating for surfaces contacting withrubber during vulcanization .of'a substantially wate'r insoluble consistcomposition comprising Montan "wax.

14. A nomadherent 'coatingfoi' surfaces contacting with rubberduringvulcsnimion consistingof a substantially waterinsolublecomposition comprisinga wax of. velge.table origin and a soft pitchfofthe asphat type.

15. A non-adherent" coating for-surfaces contacting with rubber duringvulcanization consisting of a 'substantialhli' water-insolublecomposition "comprising ontan wax and as haltum pitch.

n witness whereof .we have hereunto set our hands thislith da ofNovember, 1924.

- BE ON DALES.- WILLIAM S. CABLE.

